Example of a memory consistency error when using volatile keyword?

Question

From docs:

Using volatile variables reduces the risk of memory consistency errors

But this means that sometimes volatile variables

Answer 1

Volatile does the following:

- It prevents the caching the values in the Thread.

- It makes sure that the threads having the copies of the values of the fields of the object reconcile with the main copy present in the memory.

- Making sure the data is written directly to the memory and read from memory itself.

## But the condition where volatile fails:

- Making a Non-Atomic statement Volatile.

Eg:

int count = 0;

count++;  // Increment operator is Not Atomic in java

## Better option:

1. Its always better to follow the Brian's Rule:

When ever we write a variable which is next to be read by another thread, or when we are reading a variable which is written just by another thread, it needs to be synchronized. The shared fields must be made private, making the read and write methods/atomic statements synchronized.

2. Second option is using the Atomic Classes, like AtomicInteger, AtomicLong, AtomicReference, etc.

## See this link, i have asked a similar question like yours:

Why Volatile is behaving weirdly